Sea-level rise hotspot

Nature Climate Change

June 25, 2012

Sea levels are rising faster on the Atlantic Coast of North America than elsewhere around the world, and this rise appears to be accelerating reports a paper published online in Nature Climate Change this week. The work suggests that this will increase the vulnerability of coastal cities to flooding and damage coastal wetland habitats, especially under storm-surge conditions.

Climate warming causes sea-level rise by melting of land-based ice and also through the thermal expansion of water. However, sea-level rise is expected to vary from place to place owing to various factors such as ocean currents and differences in seawater temperature and saltiness, as well as the Earth’s rotation and shape.

The sea-level rise ‘hotspot’ identified by Asbury Sallenger and colleagues involves 1,000 kilometres of the east coast of North America north of Cape Hatteras, North Carolina. It is located in one of the world’s most densely populated coastal areas, encompassing Boston, Providence, New York City, Philadelphia, Baltimore and Norfolk-Virginia Beach. Based on an analysis of tide-gauge records, the researchers found that between 1950-1979 and 1980-2009 the rates of sea-level rise in this northeast hotspot were around three to four times higher than the global average, and consistent with the ‘fingerprint’ of sea-level rise expected from computer simulations.

The discovery of this regional hotspot of sea-level rise is likely to help predict the submergence of saltwater marshes, and help plan adaptation measures for coastal cities and communities in the face of encroaching seas. The findings will also help scientists develop and refine models of sea-level rise to reflect the real world better.